We recently reported the synthesis of a new class of beta-aminoacylpalladium(II) complexes. The parent compound, chloro(3-diethylaminopropionyl) (diethylamine) palladium(II), showed significant antitumor activity against P-388 mouse leukemia in 5-10 mg/kg dose levels. A series of related analogous palladium and platinum complexes will be synthesized and tested for antitumor activity. The synthetic procedure allows for systematic variation of structure, so that properties such as solubility and lypophilicity may be significantly changed without altering the basic structure of the complexes. Thus complexes having long aliphatic side chains, polar groups or chelating ligands will be synthesized. Further, a series of cationic complexes will be prepared by removal of halogen, and these complexes will be screened for antitumor activity. X-ray crystallographic structure determinations will be performed on complexes of interest.